Method and apparatus for subtraction-based programming of neurostimulation fields

ABSTRACT

An example of a neurostimulation system may include a programming control circuit and a stimulation control circuit. The programming control circuit may be configured to program a stimulation device for delivering the neurostimulation according to a stimulation program specifying a present stimulation field set including stimulation field(s) each defined by a set of active electrodes selected from a plurality of electrodes. The stimulation control circuit may be configured to determine the stimulation program and may include field programming circuitry that may be configured to set the present stimulation field set to an initial stimulation field set specifying stimulation fields allowing for the delivery of the neurostimulation to produce an intended effect and to identify an optimal stimulation field set that satisfies one or more optimization criteria by removing stimulation field(s) from the initial stimulation field set.

CLAIM OF PRIORITY

This application claims the benefit of priority under 35 U.S.C. § 119(e)of U.S. Provisional Patent Application Ser. No. 62/887,290, filed onAug. 15, 2019, which is herein incorporated by reference in itsentirety.

TECHNICAL FIELD

This document relates generally to medical devices and more particularlyto a method and system for programming a neurostimulation device using asubtraction-based paradigm to determine stimulation fields.

BACKGROUND

Neurostimulation, also referred to as neuromodulation, has been proposedas a therapy for a number of conditions. Examples of neurostimulationinclude Spinal Cord Stimulation (SCS), Deep Brain Stimulation (DBS),Peripheral Nerve Stimulation (PNS), and Functional ElectricalStimulation (FES). Implantable neurostimulation systems have beenapplied to deliver such a therapy. An implantable neurostimulationsystem may include an implantable neurostimulator, also referred to asan implantable pulse generator (IPG), and one or more implantable leadseach including one or more electrodes. The implantable neurostimulatordelivers neurostimulation energy through one or more electrodes placedon or near a target site in the nervous system. An external programmingdevice is used to program the implantable neurostimulator withstimulation parameters controlling the delivery of the neurostimulationenergy.

In one example, the neurostimulation energy is delivered to a patient inthe form of electrical neurostimulation pulses. The delivery iscontrolled using stimulation parameters that specify spatial (where tostimulate), temporal (when to stimulate), and informational (patterns ofpulses directing the nervous system to respond as desired) aspects of apattern of neurostimulation pulses. Stimulation parameters specifyingthe spatial aspects may determine where to place electrodes and/or whichelectrodes to select for delivering the neurostimulation pulses. Thismay include searching for locations in or on the patient that respond tothe delivery of the neurostimulation pulses with desirable therapeuticeffects as well as searching for locations in or on the patient thatrespond to the delivery of the neurostimulation pulses with undesirableside effects, such that the stimulation parameters can be determined fortherapeutic effectiveness while ensuring patient safety and minimizingside effects.

SUMMARY

An example (e.g., “Example 1”) of a system for deliveringneurostimulation to tissue of a patient using a stimulation devicecoupled to a plurality of electrodes and controlling the delivery of theneurostimulation is provided. The system may include a programmingcontrol circuit and a stimulation control circuit. The programmingcontrol circuit may be configured to program the stimulation device fordelivering the neurostimulation according to a stimulation programspecifying a present stimulation field set including one or morestimulation fields each defined by a set of active electrodes selectedfrom the plurality of electrodes. The stimulation control circuit may beconfigured to determine the stimulation program. The stimulation controlcircuit may include field programming circuitry that may be configuredto set the present stimulation field set to an initial stimulation fieldset specifying a plurality of stimulation fields and allowing for thedelivery of the neurostimulation to produce an intended effect in thepatient and to identify an optimal stimulation field set that satisfiesone or more optimization criteria by removing one or more stimulationfields from the initial stimulation field set, the optimal stimulationfield set including one or more stimulation fields based on a subset ofthe plurality of stimulation fields of the initial stimulation fieldset.

In Example 2, the subject matter of Example 1 may optionally beconfigured such that the field programming circuitry is configured tofurther define the one or more stimulation fields by a distribution ofenergy of the neurostimulation over the active electrodes.

In Example 3, the subject matter of any one or any combination ofExamples 1 and 2 may optionally be configured such that the fieldprogramming circuitry is configured to identify an optimal stimulationfield set by removing at least one stimulation field from the presentstimulation field set to update the present stimulation field set,causing the stimulation device to deliver the neurostimulation accordingto the stimulation program specifying the present stimulation field set,receiving a response signal indicative of effects of theneurostimulation delivered according to the stimulation programspecifying the present stimulation field set, reverting the presentstimulation field set to the pre-update present stimulation field set inresponse to the response signal indicating an unacceptable change to theeffects indicated by the response signal, and repeating the removing,causing, receiving, and reverting until the present stimulation fieldset is determined to be the optimal stimulation field set according tothe one or more optimization criteria.

In Example 4, the subject matter of Example 3 may optionally beconfigured to further include a user input device configured to receivea user input indicative of the patient's perception of the delivery ofthe neurostimulation, and such that the stimulation control circuitfurther includes a response input and response analysis circuitry. Theresponse input is configured to receive a response signal indicative ofeffects of the neurostimulation, the response signal including thereceived user input. The response analysis circuitry is configured toanalyze the received response signal and produce effects informationallowing for the determination of whether the present stimulation fieldis the optimal stimulation field set according to the one or moreoptimization criteria.

In Example 5, the subject matter of any one or any combination ofExamples 3 and 4 may optionally be configured such that the fieldprogramming circuitry is configured to revert the present stimulationfield set to the pre-update present stimulation field set in response tothe effects information indicating at least one of a decrease in theintended effect or an increase in an unintended effect.

In Example 6, the subject matter of Example 5 may optionally beconfigured such that the field programming circuitry is furtherconfigured to, after the reverting in response to the response signalindicating the increase in the unintended effect, add to the presentstimulation field set one or more blocking fields to which the deliveryof the neurostimulation has a blocking effect in preventing the deliveryof the neurostimulation from causing the unintended effect or reducingthe unintended effect.

In Example 7, the subject matter of Example 5 may optionally beconfigured such that the field programming circuitry is furtherconfigured to, after the reverting in response to the response signalindicating the increase in the unintended effect, modifying a shape ofthe present stimulation field set to prevent the delivery of theneurostimulation from causing the unintended effect or reduce theunintended effect.

In Example 8, the subject matter of any one or any combination ofExamples 4 to 7 may optionally be configured such that the fieldprogramming circuitry is further configured to declare the presentstimulation field set to be the optimal stimulation field set inresponse to the effects information indicating that the intended effectis maintained without causing an unintended effect.

In Example 9, the subject matter of any one or any combination ofExamples 4 to 7 may optionally be configured such that the fieldprogramming circuitry is further configured to declare the presentstimulation field set to be the optimal stimulation field set inresponse to the effects information indicating that the intended effectis maintained while one or more unintended effects are minimized.

In Example 10, the subject matter of any one or any combination ofExamples 8 and 9 may optionally be configured such that the fieldprogramming circuitry is further configured to declare the presentstimulation field set to be the optimal stimulation field set inresponse to the effects information indicating that the intended effectis maintained with energy of the delivered neurostimulation beingminimized.

In Example 11, the subject matter of any one or any combination ofExamples 4 to 7 may optionally be configured such that the fieldprogramming circuitry is further configured to identifying the optimalstimulation field set from a list of test stimulation field sets, andthe repeating comprises repeating the removing, causing, receiving, andreverting until each test stimulation field set on the list is set tothe present stimulation field set to result in the effects informationallowing for the optimal stimulation field set to identified from thelist for best satisfying the one or more optimization criteria.

In Example 12, the subject matter of any one or any combination ofExamples 1 to 11 may optionally be configured to further include thestimulation device and a programmer configured to be communicativelycoupled to the stimulation device. The programmer includes theprogramming control circuit and the stimulation control circuit.

In Example 13, the subject matter of Example 12 may optionally beconfigured such that the stimulation device comprises an implantablestimulation device, and the programmer comprises an external programmer.

An example (e.g., “Example 14”) of a non-transitory computer-readablestorage medium including instructions, which when executed by a machine,cause the machine to perform a method for delivering neurostimulation totissue of a patient using a stimulation device coupled to a plurality ofelectrodes and controlling the delivery of the neurostimulation by auser is also provided. The method may include delivering theneurostimulation according to a stimulation program specifying a presentstimulation field set including one or more stimulation fields eachdefined by a set of active electrodes selected from the plurality ofelectrodes, setting the present stimulation field set to an initialstimulation field set specifying a plurality of stimulation fields andallowing for the delivery of the neurostimulation to produce an intendedeffect in the patient, and identifying an optimal stimulation field setthat satisfies one or more optimization criteria by removing one or morestimulation fields from the initial stimulation field set. The optimalstimulation field set may include one or more stimulation fields basedon a subset of the plurality of stimulation fields of the initialstimulation field set.

In Example 15, the subject matter identifying the optimal stimulationfield set as found in Example 14 may optionally be configured to includeremoving at least one stimulation field from the present stimulationfield set to update the present stimulation field set, causing thestimulation device to deliver the neurostimulation according to thestimulation program specifying the present stimulation field set,receiving a response signal indicative of effects of theneurostimulation delivered according to the stimulation programspecifying the present stimulation field set, reverting the presentstimulation field set to the pre-update present stimulation field set inresponse to the response signal indicating an unacceptable change to theeffects indicated by the response signal, and repeating the removing,causing, receiving, and reverting until the present stimulation fieldset is determined to be the optimal stimulation field set according tothe one or more optimization criteria.

An example (e.g., “Example 16”) of a method for deliveringneurostimulation to tissue of a patient using a stimulation devicecoupled to a plurality of electrodes and controlling the delivery of theneurostimulation by a user is also provided. The method may includedelivering the neurostimulation according to a stimulation programspecifying a present stimulation field set including one or morestimulation fields each defined by a set of active electrodes selectedfrom the plurality of electrodes, setting the present stimulation fieldset to an initial stimulation field set specifying a plurality ofstimulation fields and allowing for the delivery of the neurostimulationto produce an intended effect in the patient, and identifying an optimalstimulation field set that satisfies one or more optimization criteriaby removing one or more stimulation fields from the initial stimulationfield set, the optimal stimulation field set including one or morestimulation fields based on a subset of the plurality of stimulationfields of the initial stimulation field set.

In Example 17, the subject matter of the one or more stimulation fieldsas found in Example 16 may optionally include the one or morestimulation fields each further defined by a distribution of energy ofthe neurostimulation over the active electrodes.

In Example 18, the subject matter of identifying the optimal stimulationfield set as found in any one or any combination of Examples 16 and 17may optionally include removing at least one stimulation field from thepresent stimulation field set to update the present stimulation fieldset, causing the stimulation device to deliver the neurostimulationaccording to the stimulation program specifying the present stimulationfield set, receiving a response signal indicative of effects of theneurostimulation delivered according to the stimulation programspecifying the present stimulation field set, reverting the presentstimulation field set to the pre-update present stimulation field set inresponse to the response signal indicating an unacceptable change to theeffects indicated by the response signal, and repeating the removing,causing, receiving, and reverting until the present stimulation fieldset is determined to be the optimal stimulation field set according tothe one or more optimization criteria.

In Example 19, the subject matter of receiving the response signal asfound in Example 18 may optionally include receiving a user inputindicating the patient's perception of the delivery of theneurostimulation.

In Example 20, the subject matter of reverting the present stimulationfield set to the pre-update present stimulation field set in response tothe response signal indicating the unacceptable change to the effectsindicated by the response signal as found in any one or any combinationof Examples 18 and 19 may optionally include reverting the presentstimulation field set to the pre-update present stimulation field set inresponse to the response signal indicating at least one of a decrease inthe intended effect or an increase in an unintended effect.

In Example 21, the subject matter of Example 20 may optionally furtherinclude after the reverting in response to the response signalindicating the increase in the unintended effect, adding to the presentstimulation field set one or more blocking fields to which the deliveryof the neurostimulation has a blocking effect in preventing the deliveryof the neurostimulation from causing the unintended effect or reducingthe unintended effect.

In Example 22, the subject matter of Example 20 may optionally furtherinclude after the reverting in response to the response signalindicating the increase in the unintended effect, modifying a shape ofthe present stimulation field set to prevent the delivery of theneurostimulation from causing the unintended effect or reduce theunintended effect.

In Example 23, the subject matter of any one or any combination ofExamples 18 to 22 may optionally include analyzing the received responsesignal to produce effects information allowing for determination ofwhether the present stimulation field set is the optimal stimulationfield set based on the one or more optimization criteria.

In Example 24, the subject matter of the effects information as found inExample 23 may optionally include effects information indicating theunacceptable change to the effects of the neurostimulation deliveredaccording to the stimulation program specifying the present stimulationfield set.

In Example 25, the subject matter of Example 24 may optionally furtherinclude declaring the present stimulation field set to be the optimalstimulation field set in response to the effects information indicatingthat the intended effect is maintained without causing an unintendedeffect.

In Example 26, the subject matter of Example 25 may optionally furtherinclude declaring the present stimulation field set to be the optimalstimulation field set in response to the effects information indicatingthat the intended effect is maintained with energy of the deliveredneurostimulation being minimized.

In Example 27, the subject matter of Example 24 may optionally furtherinclude declaring the present stimulation field set to be the optimalstimulation field set in response to the effects information indicatingthat the intended effect is maintained while one or more unintendedeffects are minimized.

In Example 28, the subject matter of identifying the optimal stimulationfield set as found in any one or any combination of Examples 23 to 27may optionally include identifying the optimal stimulation field setidentified from a list of test stimulation field sets, and the subjectmatter of repeating as found in any one or any combination of Examples23 to 27 may optionally include repeating the removing, causing,receiving, and reverting until each test stimulation field set on thelist is set to the present stimulation field set to result in theeffects information allowing for the optimal stimulation field set toidentified from the list for best satisfying the one or moreoptimization criteria.

This Summary is an overview of some of the teachings of the presentapplication and not intended to be an exclusive or exhaustive treatmentof the present subject matter. Further details about the present subjectmatter are found in the detailed description and appended claims. Otheraspects of the disclosure will be apparent to persons skilled in the artupon reading and understanding the following detailed description andviewing the drawings that form a part thereof, each of which are not tobe taken in a limiting sense. The scope of the present disclosure isdefined by the appended claims and their legal equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate generally, by way of example, variousembodiments discussed in the present document. The drawings are forillustrative purposes only and may not be to scale.

FIG. 1 illustrates an embodiment of a neurostimulation system.

FIG. 2 illustrates an embodiment of a stimulation device and a leadsystem, such as may be implemented in the neurostimulation system ofFIG. 1.

FIG. 3 illustrates an embodiment of a programming device, such as may beimplemented in the neurostimulation system of FIG. 1.

FIG. 4 illustrates an embodiment of an implantable pulse generator (IPG)and an implantable lead system, such as an example implementation of thestimulation device and lead system of FIG. 2.

FIG. 5 illustrates an implantable neurostimulation system, such as anexample application of the IPG and implantable lead system of FIG. 4,and portions of an environment in which the system may be used.

FIG. 6 illustrates an embodiment of portions of a neurostimulationsystem.

FIG. 7 illustrates an embodiment of an implantable stimulator and one ormore leads of an implantable neurostimulation system, such as theimplantable neurostimulation system of FIG. 6.

FIG. 8 illustrates an embodiment of an external programming device of animplantable neurostimulation system, such as the implantableneurostimulation system of FIG. 6.

FIG. 9 illustrates an embodiment of a system for optimizing astimulation field set.

FIG. 10 illustrates another embodiment of a system for optimizing astimulation field set.

FIG. 11 illustrates an embodiment of a subtraction-based programmingmethod for optimizing a stimulation field set.

FIG. 12 illustrates an embodiment of a method for identifying an optimalstimulation field set, such as used in the method of FIG. 11.

FIGS. 13A-E each illustrate an embodiment of a paddle electrode to besurgically implanted for delivering neurostimulation, with FIGS. 13B-Eeach illustrating an example of a stimulation field set.

FIGS. 14A-E each illustrate an embodiment of an electrode array atdistal end of a lead to be percutaneously implanted for deliveringneurostimulation, with FIGS. 14B-E each illustrating an example of astimulation field set.

FIG. 15 illustrates an embodiment of a subtraction-based programmingmethod as an application of the methods of FIGS. 11 and 12.

FIG. 16 illustrates another embodiment of a subtraction-basedprogramming method as an application of the methods of FIGS. 11 and 12.

FIG. 17A-F each illustrate an embodiment of part of the method of FIG.15 or 16.

FIG. 18A-E illustrates another embodiment of part of the method of FIG.15 or 16.

FIG. 19 illustrates an embodiment of tools for editing a stimulationfield set using a graphical user interface (GUI).

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that the embodiments may be combined, or that otherembodiments may be utilized and that structural, logical and electricalchanges may be made without departing from the spirit and scope of thepresent invention. References to “an”, “one”, or “various” embodimentsin this disclosure are not necessarily to the same embodiment, and suchreferences contemplate more than one embodiment. The following detaileddescription provides examples, and the scope of the present invention isdefined by the appended claims and their legal equivalents.

This document discusses, among other things, a method and system fordetermining one or more stimulation fields for a neurostimulation systemto deliver neurostimulation energy. In various embodiments, theneuromodulation system can include an implantable device configured todeliver neurostimulation (also referred to as neuromodulation)therapies, such as deep brain stimulation (DBS), spinal cord stimulation(SCS), peripheral nerve stimulation (PNS), and vagus nerve stimulation(VNS), and one or more external devices configured to program theimplantable device for its operations and monitor the performance of theimplantable device.

An effective neurostimulation therapy requires the neurostimulationenergy to be delivered to a right location in or on the patient. When animplantable electrode array is used for delivering the neurostimulationenergy, a stimulation field is to be programmed in a “right” location(known as a “sweet spot”) by specifying one or more electrodes of theelectrode array and/or a stimulation current distribution overelectrodes of the electrode array. A sweet spot can be identified bytesting one stimulation field at a time using a change-the-field (CTF)or move-the-field (MTF) paradigm. If one stimulation field does notprovide an intended effect of neurostimulation, one or more stimulationfields are tested one at a time until the intended effect is obtained.This process can include testing multiple fields by any order ofelectrode configurations (CTF) or by modifying the electrodeconfiguration in an incremental manner (MTF). A neurostimulation therapyprogram can include multiple fields in combination or one or morestimulation waveforms for desirable effects. Problems with the CTF andMTF paradigms include: (1) testing one stimulation field at time can bevery time consuming; (2) in some cases (e.g., implantation of a lead)programming is required to know whether the electrode array isadequately positioned, but whether an adequate stimulation field can beidentified using the positioned electrode array is not known until oneis identified (after extensive searching sometimes); and (3) astimulation program is often limited to one or two stimulation fields,though more stimulation fields may improve therapy efficacy, becauseeach additional stimulation field may require significantly more time toidentify (sweet spots need not be contiguous or near one another, butcan be identified at different locations on the electrode array).

During the implantation of a lead including an electrode array, in anoperation room, a goal is to place the electrode array in a locationallowing neurostimulation to be delivered to result in a response thatindicates potential therapeutic efficacy. In various embodiments, theresponses can include perception of the neurostimulation by the patient,including but not limited to paresthesia. One or more stimulation fieldscan be identified, for example to maximize therapeutic effectiveness,minimize side effects, or optimize the therapy by reaching a desirablebalance between therapeutic effectiveness and side effects. Thisidentification or optimization process can be performedpost-operationally to minimize the duration of the operation (e.g., theimplantation of a neurostimulation system). In other words, the sweetspot(s) can be identified post-operationally while an adequate locationfor the electrode array is to be determined during the operation. Thisadequate location for the electrode array can be identified quickly bydelivering the neurostimulation to many stimulation fields, for examplein a sequential manner, without searching for the sweet spot(s) using atechnique such as CTF or MTF.

The present subject matter provides for a subtraction-based or“reductionist” programming paradigm for identifying one or more optimalstimulation fields. A stimulation field is considered “optimal” or“optimized” for being the field identified from a group of teststimulation fields as the best to meet one or more specified criteria.The one or more specified criteria can include, but are not limited to,requirements for achieving certain therapy efficacy, avoiding orminimizing adverse side effects, providing for energy efficiency (e.g.,when the therapy is delivered by a battery-powered system), and/orensuring patient safety. The subtraction-based programming starts withtesting many stimulation fields, for example in a sequential manner, toachieve therapy efficacy. A subtraction-based iterative process followsby removing (i.e., subtracting) a set of one or more stimulation fieldsand evaluating the response for the one or more specified criteria foreach iteration, until the one or more optimal stimulation fields areidentified.

In this document, unless noted otherwise, a “patient” includes a personwho receives or is intended to receive treatment delivered from aneurostimulation system according to the present subject matter, and a“user” includes a clinician or other caregiver who sets up theneurostimulation system for and/or treats the patient using theneurostimulation system.

FIG. 1 illustrates an embodiment of a neurostimulation system 100.System 100 includes electrodes 106, a stimulation device 104, and aprogramming device 102. Electrodes 106 are configured to be placed on ornear one or more neural targets in a patient. Stimulation device 104 isconfigured to be electrically connected to electrodes 106 and deliverneurostimulation energy, such as in the form of electrical pulses, tothe one or more neural targets though electrodes 106. The delivery ofthe neurostimulation is controlled by using a plurality of stimulationparameters, such as stimulation parameters specifying a pattern of theelectrical pulses and a selection of electrodes through which each ofthe electrical pulses is delivered. In various embodiments, at leastsome parameters of the plurality of stimulation parameters areprogrammable by the user. Programming device 102 provides the user withaccessibility to the user-programmable parameters. In variousembodiments, programming device 102 is configured to be communicativelycoupled to stimulation device via a wired or wireless link. In variousembodiments, the patient can be allowed to adjust his or her treatmentusing system 100 to certain extent, such as by adjusting certain therapyparameters and entering feedback and clinical effect information.

In various embodiments, programming device 102 can include a userinterface 110 that allows the user to control the operation of system100 and monitor the performance of system 100 as well as conditions ofthe patient including responses to the delivery of the neurostimulation.The user can control the operation of system 100 by setting and/oradjusting values of the user-programmable parameters.

In various embodiments, user interface 110 can include a graphical userinterface (GUI) that allows the user to set and/or adjust the values ofthe user-programmable parameters by creating and/or editing graphicalrepresentations of various waveforms. Such waveforms may include, forexample, a waveform representing a pattern of neurostimulation pulses tobe delivered to the patient as well as individual waveforms that areused as building blocks of the pattern of neurostimulation pulses, suchas the waveform of each pulse in the pattern of neurostimulation pulses.The GUI may also allow the user to set and/or adjust stimulation fieldseach defined by a set of electrodes through which one or moreneurostimulation pulses represented by a waveform are delivered to thepatient. The stimulation fields may each be further defined by thedistribution of the current of each neurostimulation pulse in thewaveform. In various embodiments, neurostimulation pulses for astimulation period (such as the duration of a therapy session) may bedelivered to multiple stimulation fields.

In various embodiments, system 100 can be configured forneurostimulation applications. User interface 110 can be configured toallow the user to control the operation of system 100 forneurostimulation. For example, system 100 as well as user interface 100can be configured for SCS applications. While an SCS system isillustrated and discussed as an example, the present subject matterapplies to any neurostimulation system with electrodes placed inlocations suitable for sensing one or more neural signals from whichindications of degenerative and/or other nerve diseases can be detectedand monitored.

FIG. 2 illustrates an embodiment of a stimulation device 204 and a leadsystem 208, such as may be implemented in neurostimulation system 100.Stimulation device 204 represents an example of stimulation device 104and includes a stimulation output circuit 212 and a stimulation controlcircuit 214. Stimulation output circuit 212 produces and deliversneurostimulation pulses. Stimulation control circuit 214 controls thedelivery of the neurostimulation pulses from stimulation output circuit212 using the plurality of stimulation parameters, which specifies apattern of the neurostimulation pulses. Lead system 208 includes one ormore leads each configured to be electrically connected to stimulationdevice 204 and a plurality of electrodes 206 distributed in the one ormore leads. The plurality of electrodes 206 includes electrode 206-1,electrode 206-2, . . . electrode 206-N, each a single electricallyconductive contact providing for an electrical interface betweenstimulation output circuit 212 and tissue of the patient, where N≥2. Theneurostimulation pulses are each delivered from stimulation outputcircuit 212 through a set of electrodes selected from electrodes 206. Invarious embodiments, the neurostimulation pulses may include one or moreindividually defined pulses, and the set of electrodes may beindividually definable by the user for each of the individually definedpulses or each of collections of pulses intended to be delivered usingthe same combination of electrodes. In various embodiments, one or moreadditional electrodes 207 (each of which may be referred to as areference electrode) can be electrically connected to stimulation device204, such as one or more electrodes each being a portion of or otherwiseincorporated onto a housing of stimulation device 204. Monopolarstimulation uses a monopolar electrode configuration with one or moreelectrodes selected from electrodes 206 and at least one electrode fromelectrode(s) 207. Bipolar stimulation uses a bipolar electrodeconfiguration with two electrodes selected from electrodes 206 and noneelectrode(s) 207. Multipolar stimulation uses a multipolar electrodeconfiguration with multiple (two or more) electrodes selected fromelectrodes 206 and optionally electrode(s) 207.

In various embodiments, the number of leads and the number of electrodeson each lead depend on, for example, the distribution of target(s) ofthe neurostimulation and the need for controlling the distribution ofelectric field at each target. In one embodiment, lead system 208includes 2 leads each having 8 electrodes. Lead and electrodeconfigurations are illustrated in this document as examples and notlimitations. For example, various embodiments can use paddle electrodes,cuff electrodes, and other electrodes suitable for deliveringneurostimulation.

FIG. 3 illustrates an embodiment of a programming device 302, such asmay be implemented in neurostimulation system 100. Programming device302 represents an example of programming device 102 and includes astorage device 318, a programming control circuit 316, and a userinterface 310. Programming control circuit 316 generates the pluralityof stimulation parameters that controls the delivery of theneurostimulation pulses according to a specified neurostimulationprogram that can define, for example, stimulation waveform and electrodeconfiguration. User interface 310 represents an example of userinterface 110 and includes a stimulation control circuit 320. Storagedevice 318 stores information used by programming control circuit 316and stimulation control circuit 320, such as information about astimulation device that relates the neurostimulation program to theplurality of stimulation parameters. In various embodiments, stimulationcontrol circuit 320 can be configured to support one or more functionsallowing for programming of stimulation devices, such as stimulationdevice 104 including its various embodiments as discussed in thisdocument, according to one or more selected neurostimulation programs asdiscussed in this document.

In various embodiments, user interface 310 can allow for definition of apattern of neurostimulation pulses for delivery during aneurostimulation therapy session by creating and/or adjusting one ormore stimulation waveforms using a graphical method. The definition canalso include definition of one or more stimulation fields eachassociated with one or more pulses in the pattern of neurostimulationpulses. As used in this document, a “neurostimulation program” caninclude the pattern of neurostimulation pulses including the one or morestimulation fields, or at least various aspects or parameters of thepattern of neurostimulation pulses including the one or more stimulationfields. In various embodiments, user interface 310 includes a GUI thatallows the user to define the pattern of neurostimulation pulses andperform other functions using graphical methods. In this document,“neurostimulation programming” can include the definition of the one ormore stimulation waveforms, including the definition of one or morestimulation fields.

In various embodiments, circuits of neurostimulation 100, including itsvarious embodiments discussed in this document, may be implemented usinga combination of hardware and software. For example, the circuit of userinterface 110, stimulation control circuit 214, programming controlcircuit 316, and stimulation control circuit 320, including theirvarious embodiments discussed in this document, may be implemented usingan application-specific circuit constructed to perform one or moreparticular functions or a general-purpose circuit programmed to performsuch function(s). Such a general-purpose circuit can include, but is notlimited to, a microprocessor or a portion thereof, a microcontroller orportions thereof, and/or a programmable logic circuit or a portionthereof.

FIG. 4 illustrates an embodiment of an implantable pulse generator (IPG)404 and an implantable lead system 408. IPG 404 represents an exampleimplementation of stimulation device 204. Lead system 408 represents anexample implementation of lead system 208. As illustrated in FIG. 4, IPG404 that can be coupled to implantable leads 408A and 408B at a proximalend of each lead. The distal end of each lead includes electricalcontacts or electrodes 406 for contacting a tissue site targeted forelectrical neurostimulation. As illustrated in FIG. 1, leads 408A and408B each include 8 electrodes 406 at the distal end. The number andarrangement of leads 408A and 408B and electrodes 406 as shown in FIG. 1are only an example, and other numbers and arrangements are possible. Invarious embodiments, the electrodes are ring electrodes. The implantableleads and electrodes may be configured by shape and size to provideelectrical neurostimulation energy to a neuronal target included in thesubject's brain or configured to provide electrical neurostimulationenergy to target nerve cells in the subject's spinal cord.

FIG. 5 illustrates an implantable neurostimulation system 500 andportions of an environment in which system 500 may be used. System 500includes an implantable system 521, an external system 502, and atelemetry link 540 providing for wireless communication betweenimplantable system 521 and external system 502. Implantable system 521is illustrated in FIG. 5 as being implanted in the patient's body 599.

Implantable system 521 includes an implantable stimulator (also referredto as an implantable pulse generator, or IPG) 504, a lead system 508,and electrodes 506, which represent an example of stimulation device204, lead system 208, and electrodes 206, respectively. External system502 represents an example of programming device 302. In variousembodiments, external system 502 includes one or more external(non-implantable) devices each allowing the user and/or the patient tocommunicate with implantable system 521. In some embodiments, externalsystem 502 includes a programming device intended for the user toinitialize and adjust settings for implantable stimulator 504 and aremote control device intended for use by the patient. For example, theremote control device may allow the patient to turn implantablestimulator 504 on and off and/or adjust certain patient-programmableparameters of the plurality of stimulation parameters.

The sizes and shapes of the elements of implantable system 521 and theirlocation in body 599 are illustrated by way of example and not by way ofrestriction. An implantable system is discussed as a specificapplication of the programming according to various embodiments of thepresent subject matter. In various embodiments, the present subjectmatter may be applied in programming any type of stimulation device thatuses electrical pulses as stimuli, regardless of stimulation targets inthe patient's body and whether the stimulation device is implantable.

Returning to FIG. 4, the IPG 404 can include a hermetically-sealed IPGcase 422 to house the electronic circuitry of IPG 404. IPG 404 caninclude an electrode 426 formed on IPG case 422. IPG 404 can include anIPG header 424 for coupling the proximal ends of leads 408A and 408B.IPG header 424 may optionally also include an electrode 428. Electrodes426 and/or 428 represent embodiments of electrode(s) 207 and may each bereferred to as a reference electrode. Neurostimulation energy can bedelivered in a monopolar (also referred to as unipolar) mode usingelectrode 426 or electrode 428 and one or more electrodes selected fromelectrodes 406. Neurostimulation energy can be delivered in a bipolarmode using a pair of electrodes of the same lead (lead 408A or lead408B). Neurostimulation energy can be delivered in an extended bipolarmode using one or more electrodes of a lead (e.g., one or moreelectrodes of lead 408A) and one or more electrodes of a different lead(e.g., one or more electrodes of lead 408B).

The electronic circuitry of IPG 404 can include a control circuit thatcontrols delivery of the neurostimulation energy. The control circuitcan include a microprocessor, a digital signal processor, applicationspecific integrated circuit (ASIC), or other type of processor,interpreting or executing instructions included in software or firmware.The neurostimulation energy can be delivered according to specified(e.g., programmed) modulation parameters. Examples of setting modulationparameters can include, among other things, selecting the electrodes orelectrode combinations used in the stimulation, configuring an electrodeor electrodes as the anode or the cathode for the stimulation,specifying the percentage of the neurostimulation provided by anelectrode or electrode combination, and specifying stimulation pulseparameters. Examples of pulse parameters include, among other things,the amplitude of a pulse (specified in current or voltage), pulseduration (e.g., in microseconds), pulse rate (e.g., in pulses persecond), and parameters associated with a pulse train or pattern such asburst rate (e.g., an “on” modulation time followed by an “off”modulation time), amplitudes of pulses in the pulse train, polarity ofthe pulses, etc.

FIG. 6 illustrates an embodiment of portions of a neurostimulationsystem 600. System 600 includes an IPG 604, implantable neurostimulationleads 608A and 608B, an external remote controller (RC) 632, aclinician's programmer (CP) 630, and an external trial stimulator (ETS,also referred to as external trial modulator, or ETM) 634. IPG 404 maybe electrically coupled to leads 608A and 608B directly or throughpercutaneous extension leads 636. ETS 634 may be electricallyconnectable to leads 608A and 608B via one or both of percutaneousextension leads 636 and/or external cable 638. System 600 represents anexample of system 100, with IPG 604 representing an embodiment ofstimulation device 104, electrodes 606 of leads 608A and 608Brepresenting electrodes 106, and CP 630, RC 632, and ETS 634collectively representing programming device 102.

ETS 634 may be standalone or incorporated into CP 630. ETS 634 may havesimilar pulse generation circuitry as JPG 604 to deliverneurostimulation energy according to specified modulation parameters asdiscussed above. ETS 634 is an external device configured for ambulatoryuse and may be used as a preliminary stimulator after leads 408A and408B have been implanted and used prior to stimulation with IPG 604 totest the patient's responsiveness to the stimulation that is to beprovided by IPG 604. ETS 634 may include cable connectors allowing it toreadily interface the proximal end of external leads that are forchronic use, and may include replaceable batteries.

CP 630 can configure the neurostimulation provided by ETS 634. If ETS634 is not integrated into CP 630, CP 630 may communicate with ETS 634using a wired connection (e.g., over a USB link) or by wirelesstelemetry using a wireless communications link 640. CP 630 alsocommunicates with IPG 604 using a wireless communications link 640.

An example of wireless telemetry is based on inductive coupling betweentwo closely-placed coils using the mutual inductance between thesecoils. This type of telemetry is referred to as inductive telemetry ornear-field telemetry because the coils must typically be closelysituated for obtaining inductively coupled communication. IPG 604 caninclude the first coil and a communication circuit. CP 630 can includeor be otherwise electrically connected to the second coil such as in theform of a wand that can be place near IPG 604. Another example ofwireless telemetry includes a far-field telemetry link, also referred toas a radio frequency (RF) telemetry link. A far-field, also referred toas the Fraunhofer zone, refers to the zone in which a component of anelectromagnetic field produced by the transmitting electromagneticradiation source decays substantially proportionally to 1/r, where r isthe distance between an observation point and the radiation source.Accordingly, far-field refers to the zone outside the boundary ofr=λ/2π, where λ is the wavelength of the transmitted electromagneticenergy. In one example, a communication range of an RF telemetry link isat least six feet but can be as long as allowed by the particularcommunication technology. RF antennas can be included, for example, inthe header of IPG 604 and in the housing of CP 630, eliminating the needfor a wand or other means of inductive coupling. An example is such anRF telemetry link is a Bluetooth® wireless link.

CP 630 can be used to set modulation parameters for the neurostimulationafter IPG 604 has been implanted. This allows the neurostimulation to betuned if the requirements for the neurostimulation change afterimplantation. CP 630 can also upload information from IPG 604.

RC 632 also communicates with IPG 604 using a wireless link 340. RC 632may be a communication device used by the user or given to the patient.RC 632 may have reduced programming capability compared to CP 630. Thisallows the user or patient to alter the neurostimulation therapy butdoes not allow the patient full control over the therapy. For example,the patient may be able to increase the amplitude of neurostimulationpulses or change the time that a preprogrammed stimulation pulse trainis applied. RC 632 may be programmed by CP 630. CP 630 may communicatewith the RC 632 using a wired or wireless communications link. In someembodiments, CP 630 can program RC 632 when remotely located from RC632.

FIG. 7 illustrates an embodiment of implantable stimulator 704 and oneor more leads 708 of an implantable neurostimulation system, such asimplantable system 600. Implantable stimulator 704 represents an exampleof stimulation device 104 or 204 and may be implemented, for example, asIPG 604. Lead(s) 708 represents an example of lead system 208 and may beimplemented, for example, as implantable leads 608A and 608B. Lead(s)708 includes electrodes 706, which represents an example of electrodes106 or 206 and may be implemented as electrodes 606.

Implantable stimulator 704 may include a sensing circuit 742 that isoptional and required only when the stimulator needs a sensingcapability, stimulation output circuit 212, a stimulation controlcircuit 714, an implant storage device 746, an implant telemetry circuit744, a power source 748, and one or more electrodes 707. Sensing circuit742 senses one or more physiological signals for purposes of patientmonitoring and/or feedback control of the neurostimulation. Examples ofthe one or more physiological signals include neural and other signalseach indicative of a condition of the patient that is treated by theneurostimulation and/or a response of the patient to the delivery of theneurostimulation. In various embodiments, sensing circuit 742 senses oneor more neural signals and detects one or more indications of aneurodegenerative disease, as further discussed with reference to FIGS.9-16. Stimulation output circuit 212 is electrically connected toelectrodes 706 through one or more leads 708 as well as electrodes 707and delivers each of the neurostimulation pulses through a set ofelectrodes selected from electrodes 706 and electrode(s) 707.Stimulation control circuit 714 represents an example of stimulationcontrol circuit 214 and controls the delivery of the neurostimulationpulses using the plurality of stimulation parameters specifying thepattern of neurostimulation pulses. In one embodiment, stimulationcontrol circuit 714 controls the delivery of the neurostimulation pulsesusing the one or more sensed physiological signals. Implant telemetrycircuit 744 provides implantable stimulator 704 with wirelesscommunication with another device such as CP 630 and RC 632, includingreceiving values of the plurality of stimulation parameters from theother device. Implant storage device 746 can store one or moreneurostimulation programs and values of the plurality of stimulationparameters for each of the one or more neurostimulation programs. Powersource 748 provides implantable stimulator 704 with energy for itsoperation. In one embodiment, power source 748 includes a battery. Inone embodiment, power source 748 includes a rechargeable battery and abattery charging circuit for charging the rechargeable battery. Implanttelemetry circuit 744 may also function as a power receiver thatreceives power transmitted from an external device through an inductivecouple. Electrode(s) 707 allow for delivery of the neurostimulationpulses in the monopolar mode. Examples of electrode(s) 707 includeelectrode 426 and electrode 418 in IPG 404 as illustrated in FIG. 4.

In one embodiment, implantable stimulator 704 is used as a masterdatabase. A patient implanted with implantable stimulator 704 (such asmay be implemented as IPG 604) may therefore carry patient informationneeded for his or her medical care when such information is otherwiseunavailable. Implant storage device 746 is configured to store suchpatient information. For example, the patient may be given a new RC 632and/or travel to a new clinic where a new CP 630 is used to communicatewith the device implanted in him or her. The new RC 632 and/or CP 630can communicate with implantable stimulator 704 to retrieve the patientinformation stored in implant storage device 746 through implanttelemetry circuit 744 and wireless communication link 640 and allow forany necessary adjustment of the operation of implantable stimulator 704based on the retrieved patient information. In various embodiments, thepatient information to be stored in implant storage device 746 mayinclude, for example, positions of lead(s) 708 and electrodes 706relative to the patient's anatomy (transformation for fusingcomputerized tomogram (CT) of post-operative lead placement to magneticresonance imaging (MRI) of the brain), clinical effect map data,objective measurements using quantitative assessments of symptoms (forexample using micro-electrode recording, accelerometers, and/or othersensors), and/or any other information considered important or usefulfor providing adequate care for the patient. In various embodiments, thepatient information to be stored in implant storage device 746 mayinclude data transmitted to implantable stimulator 704 for storage aspart of the patient information and data acquired by implantablestimulator 704, such as by using sensing circuit 742.

In various embodiments, sensing circuit 742 (if included), stimulationoutput circuit 212, stimulation control circuit 714, implant telemetrycircuit 744, implant storage device 746, and power source 748 areencapsulated in a hermetically sealed implantable housing or case, andelectrode(s) 707 are formed or otherwise incorporated onto the case. Invarious embodiments, lead(s) 708 are implanted such that electrodes 706are placed on and/or around one or more targets to which theneurostimulation pulses are to be delivered, while implantablestimulator 704 is subcutaneously implanted and connected to lead(s) 708at the time of implantation.

FIG. 8 illustrates an embodiment of an external programming device 802of an implantable neurostimulation system, such as system 600. Externalprogramming device 802 represents an example of programming device 102or 302, and may be implemented, for example, as CP 630 and/or RC 632.External programming device 802 includes an external telemetry circuit852, an external storage device 818, a programming control circuit 816,and a user interface 810.

External telemetry circuit 852 provides external programming device 802with wireless communication with another device such as implantablestimulator 704 via wireless communication link 640, includingtransmitting the plurality of stimulation parameters to implantablestimulator 704 and receiving information including the patient data fromimplantable stimulator 704. In one embodiment, external telemetrycircuit 852 also transmits power to implantable stimulator 704 throughan inductive couple.

In various embodiments, wireless communication link 640 can include aninductive telemetry link (near-field telemetry link) and/or a far-fieldtelemetry link (RF telemetry link). For example, because DBS is oftenindicated for movement disorders which are assessed through patientactivities, gait, balance, etc., allowing patient mobility duringprogramming and assessment is useful. Therefore, when system 600 isintended for applications including DBS, wireless communication link 640includes at least a far-field telemetry link that allows forcommunications between external programming device 802 and implantablestimulator 704 over a relative long distance, such as up to about 20meters. External telemetry circuit 852 and implant telemetry circuit 744each include an antenna and RF circuitry configured to support suchwireless telemetry.

External storage device 818 stores one or more stimulation waveforms fordelivery during a neurostimulation therapy session, such as a DBStherapy session, as well as various parameters and building blocks fordefining one or more waveforms. The one or more stimulation waveformsmay each be associated with one or more stimulation fields and representa pattern of neurostimulation pulses to be delivered to the one or morestimulation fields during the neurostimulation therapy session. Invarious embodiments, each of the one or more stimulation waveforms canbe selected for modification by the user and/or for use in programming astimulation device such as implantable stimulator 704 to deliver atherapy. In various embodiments, each waveform in the one or morestimulation waveforms is definable on a pulse-by-pulse basis, andexternal storage device 818 may include a pulse library that stores oneor more individually definable pulse waveforms each defining a pulsetype of one or more pulse types. External storage device 818 also storesone or more individually definable stimulation fields. Each waveform inthe one or more stimulation waveforms is associated with at least onefield of the one or more individually definable stimulation fields. Eachfield of the one or more individually definable stimulation fields isdefined by a set of electrodes through a neurostimulation pulse isdelivered. In various embodiments, each field of the one or moreindividually definable fields is defined by the set of electrodesthrough which the neurostimulation pulse is delivered and a currentdistribution of the neurostimulation pulse over the set of electrodes.In one embodiment, the current distribution is defined by assigning afraction of an overall pulse amplitude to each electrode of the set ofelectrodes. Such definition of the current distribution may be referredto as “fractionalization” in this document. In another embodiment, thecurrent distribution is defined by assigning an amplitude value to eachelectrode of the set of electrodes. For example, the set of electrodesmay include 2 electrodes used as the anode and an electrode as thecathode for delivering a neurostimulation pulse having a pulse amplitudeof 4 mA. The current distribution over the 2 electrodes used as theanode needs to be defined. In one embodiment, a percentage of the pulseamplitude is assigned to each of the 2 electrodes, such as 75% assignedto electrode 1 and 25% to electrode 2. In another embodiment, anamplitude value is assigned to each of the 2 electrodes, such as 3 mAassigned to electrode 1 and 1 mA to electrode 2. Control of the currentin terms of percentages allows precise and consistent distribution ofthe current between electrodes even as the pulse amplitude is adjusted.It is suited for thinking about the problem as steering a stimulationlocus, and stimulation changes on multiple contacts simultaneously tomove the locus while holding the stimulation amount constant. Controland displaying the total current through each electrode in terms ofabsolute values (e.g. mA) allows precise dosing of current through eachspecific electrode. It is suited for changing the current one contact ata time (and allows the user to do so) to shape the stimulation like apiece of clay (pushing/pulling one spot at a time).

Programming control circuit 816 represents an example of programmingcontrol circuit 316 and generates the plurality of stimulationparameters, which is to be transmitted to implantable stimulator 704,based on a specified neurostimulation program (e.g., the pattern ofneurostimulation pulses as represented by one or more stimulationwaveforms and one or more stimulation fields, or at least certainaspects of the pattern). The neurostimulation program may be createdand/or adjusted by the user using user interface 810 and stored inexternal storage device 818. In various embodiments, programming controlcircuit 816 can check values of the plurality of stimulation parametersagainst safety rules to limit these values within constraints of thesafety rules. In one embodiment, the safety rules are heuristic rules.

User interface 810 represents an example of user interface 310 andallows the user to define the pattern of neurostimulation pulses andperform various other monitoring and programming tasks. User interface810 includes a display screen 856, a user input device 858, and aninterface control circuit 854. Display screen 856 may include any typeof interactive or non-interactive screens, and user input device 858 mayinclude any type of user input devices that supports the variousfunctions discussed in this document, such as touchscreen, keyboard,keypad, touchpad, trackball, joystick, and mouse. In one embodiment,user interface 810 includes a GUI. The GUI may also allow the user toperform any functions discussed in this document where graphicalpresentation and/or editing are suitable as may be appreciated by thoseskilled in the art.

Interface control circuit 854 controls the operation of user interface810 including responding to various inputs received by user input device858 and defining the one or more stimulation waveforms. Interfacecontrol circuit 854 includes stimulation control circuit 320.

In various embodiments, external programming device 802 can haveoperation modes including a composition mode and a real-time programmingmode. Under the composition mode (also known as the pulse patterncomposition mode), user interface 810 is activated, while programmingcontrol circuit 816 is inactivated. Programming control circuit 816 doesnot dynamically updates values of the plurality of stimulationparameters in response to any change in the one or more stimulationwaveforms. Under the real-time programming mode, both user interface 810and programming control circuit 816 are activated. Programming controlcircuit 816 dynamically updates values of the plurality of stimulationparameters in response to changes in the set of one or more stimulationwaveforms and transmits the plurality of stimulation parameters with theupdated values to implantable stimulator 704.

FIG. 9 illustrates an embodiment of a system 960 for optimizing astimulation field set according to a subtraction-based programmingparadigm. System 960 can be implemented as part of a system fordelivering neurostimulation to tissue of a patient using a stimulationdevice coupled to a plurality of electrodes and controlling the deliveryof the neurostimulation by a user, such as neurostimulation system 100,500, or 600. When system 960 is implemented in system 100, 500, or 600,the stimulation device can include stimulation device 104, stimulationdevice 204, IPG 404, implantable stimulator or IPG 504, IPG 604, orimplantable stimulator 704, and the plurality of electrodes can includeelectrodes 106, 206, 406, 506, 606, and 706.

System 960 can include a programming control circuit 916 and astimulation control circuit 920. Programming control circuit 916 canprogram the stimulation device for delivering the neurostimulationaccording to a stimulation program. The stimulation program specifies apresent stimulation field set including one or more stimulation fieldseach defined by a set of active electrodes selected from the pluralityof electrodes. Stimulation control circuit 920 can determine thestimulation program and include field programming circuitry 962. Fieldprogramming circuitry 962 can set the present stimulation field set toan initial stimulation field set. The initial stimulation field setspecifies a plurality of stimulation fields and allows for the deliveryof the neurostimulation to produce an intended effect in the patient.Field programming circuitry 962 can then identify an optimal stimulationfield set that satisfies one or more optimization criteria by removingone or more stimulation fields from the initial stimulation field set.

In one embodiment, the one or more stimulation fields in eachstimulation field set are each further defined by a distribution ofenergy of the neurostimulation over the active electrodes. Thedistribution of energy can be specified by specifying a percentage ofcurrent of the neurostimulation on each of the active electrodes (i.e.,by fractionalization). An equivalent way for defining the one or morestimulation fields in each stimulation field set is to specify adistribution of energy of the neurostimulation over the plurality ofelectrodes (i.e., all the electrodes, with zero energy or zero percentof current specified for each inactive electrode).

In various embodiments, system 960 may be implemented as part ofexternal programming device 802 (which may be implemented, for example,as CP 630 and/or RC 632) or implemented as any device allowing fordetermination of stimulation parameters, including any computerprogrammed for determining stimulation parameters. System 960 caninclude programming control circuit 816 and stimulation control circuit920. Programming control circuit 916 can represent an example ofprogramming control circuit 816 and can be configured to program astimulation device, such as stimulation device 104 including but notlimited to its various embodiments as discussed in this document, fordelivering neurostimulation according to a pattern of neurostimulationpulses defined by one or more stimulation waveforms. Stimulation controlcircuit 920 can represent an example of stimulation control circuit 320and can be configured to determine the neurostimulation program. Anexample of the neurostimulation program includes the stimulation programfor controlling the delivery of the neurostimulation in performing amethod of optimizing the stimulation field set according to thesubtraction-based programming paradigm.

In various embodiments, the stimulation program defined by stimulationcontrol circuit 920 can include a pattern of neurostimulation pulses.Programming control circuit 916 can generate a plurality of stimulationparameters according to the pattern of neurostimulation pulses. Inembodiments in which programming control circuit 916 is part of aprogramming device such as external programming device 802, programmingcontrol circuit 916 can transmit the plurality of stimulation parametersto implantable stimulator 704 to be used by stimulation control circuit714 to control delivery of neurostimulation from stimulation outputcircuit 212. In various embodiments, the pattern of neurostimulationpulses are defined by the one or more stimulation waveforms and one ormore stimulation fields. Stimulation control circuit 320 can determinethe one or more stimulation waveforms and the one or more stimulationfields. Each pulse in the pattern of neurostimulation pulses has astimulation waveform being the waveform of the pulse and a stimulationfield specifying electrodes through which the pulse is delivered. Theone or more stimulation fields can each be defined by a set of activeelectrodes through which one or more neurostimulation pulses of thepattern of neurostimulation pulses are delivered to the patient. Invarious embodiments, each neurostimulation pulse has an overall currentamplitude, and the one or more stimulation fields are each furtherdefined by a fractionalization assigning a fraction of the overallcurrent amplitude to each electrode of the set of active electrodes.

FIG. 10 illustrates another embodiment of a system 1060 for optimizing astimulation field set according to the subtraction-based programmingparadigm. System 1060 represents an example of system 960 and caninclude programming control circuit 916 and a stimulation controlcircuit 1020.

Stimulation control circuit 1020 represents an example of stimulationcontrol circuit 1020 and can include a response input 1064, responseanalysis circuitry 1066, and field programming circuitry 1062. Responseinput 1064 can receive a response signal indicative of effects of theneurostimulation. In one embodiment, response input 1064 can receive theresponse signal from a user input device such as user input device 858.The response signal can include a user input indicating the patient'sperception of the delivery of the neurostimulation. In anotherembodiment, response input 1064 can receive the response signal from asensing circuit, such as sensing circuit 742. The response signal caninclude a sensed biomarker signal indicative of effects of the deliveryof the neurostimulation in the patient. This allows for the stimulationfield set to be optimized automatically using a closed-loop system thatcan be implemented within the stimulation device such as implantablestimulator 704 or implemented with the programming device such asexternal programming device 802 receiving the sensed biomarker signalfrom the stimulation device or a separate sensing device.

Response analysis circuitry 1066 can analyze the response signalreceived by response input 1064 for intended and unintended effects ofthe neurostimulation and produce effects information based on theanalysis. The effects information allows for determination of whether astimulation field set is optimized based on one or more optimizationcriteria. In various embodiments, the one or more optimization criteriacan include an intended effect threshold level for a measure of anintended effect and an unintended effect threshold level for a measureof an unintended effect. The measures for the intended and unintendedeffect can each include a patient perception and/or a parameter measuredfrom a sensed biomarker signal. In this document, an “intended effect”(also referred to as a therapeutic effect or a stimulation target)includes a therapeutic or other desirable effect of theneurostimulation, and an “unintended effect” (also referred to as a sideeffect) includes an undesirable effect of the neurostimulation. Invarious embodiments, the one or more optimization criteria can include,for example, (i) maintaining an intended effect without causing anunintended effect, (ii) maintaining an intended effect above anacceptable level while minimizing an unintended effect, (iii) maximizingan intended effect while maintaining an unintended effect below anacceptable level, or (iv) maintaining an intended effect above anacceptable level and maintaining an unintended effect below anacceptable level. The unintended effect can be any unintended effect,any unacceptable unintended effect, or a specified type of unintendedeffect. In various embodiment, the one or more optimization criteria canfurther include minimizing an amount of the neurostimulation requiredfor each of (i)-(iv). A stimulation field set can be considered to be“optimized” or declared to be an “optimal” stimulation field set when itsatisfies the one or more optimization criteria or when it is the bestof a group of stimulation field sets in view of the one or moreoptimization criteria.

Field programming circuitry 1062 represents an example of fieldprogramming circuitry 962 and can perform a method for determining thestimulation program for identifying an optimal stimulation field set forthe patient. Field programming circuitry 1062 can perform the method byexecuting a subtraction-based programming algorithm to determine theoptimal stimulation field set. The method, including its variousembodiments, is discussed below as examples of a method or steps of themethod with reference to FIGS. 11-19. In one embodiment, a storagedevice (e.g., external storage device 818 when system 1060 isimplemented in external programming device 802) can include anon-transitory computer-readable storage medium including instructions,which when executed by a processor of stimulation control circuit 1020,cause the processor (or portion thereof) to perform the method(including any method or various steps of the method discussed in thisdocument, for example with reference to FIGS. 11-19). In variousembodiments, the method is performed for purposes of determining astimulation program including parameters defining one or morestimulation field for delivering a neurostimulation therapy to thepatient.

FIG. 11 illustrates an embodiment of a subtraction-based programmingmethod 1170 for optimizing a stimulation field set according to thesubtraction-based programming paradigm. In one embodiment, method 1170is performed using a neurostimulation system that includes system 960 or1060. The neurostimulation system can deliver neurostimulation to tissueof a patient using a stimulation device coupled to a plurality ofelectrodes and controlling the delivery of the neurostimulation by auser.

At 1171, the neurostimulation is delivered according to a stimulationprogram. The stimulation program specifies a present stimulation fieldset including one or more stimulation fields each defined by a set ofactive electrodes selected from the plurality of electrodes. At 1172,the present stimulation field set is set to an initial stimulation fieldset specifying a plurality of stimulation fields. The initialstimulation field allows for the delivery of the neurostimulation toproduce an intended effect in the patient. At 1173, an optimalstimulation field set that satisfies one or more optimization criteriais identified by removing one or more stimulation fields from theinitial stimulation field set. The optimal stimulation field setincludes one or more stimulation fields being a subset of the pluralityof stimulation fields of the initial stimulation field set. In oneembodiment, the one or more stimulation fields are each further definedby a distribution of energy of the neurostimulation over the activeelectrodes. After each setting (update) of the present stimulation fieldset, the stimulation device delivers the neurostimulation according tothe stimulation program specifying the newly uprated present stimulationfield set.

FIG. 12 illustrates an embodiment of a method 1275 for identifying anoptimal stimulation field set, such as used in method 1170 forperforming step 1173. In one embodiment, method 1275 is also performedusing the neurostimulation system that includes system 960 or 1060, asdiscussed for method 1170.

At 1276, at least one stimulation field is removed from the presentstimulation field set to update the present stimulation field set. At1277, the stimulation device is caused (by programming) to deliver theneurostimulation according to the stimulation program specifying thepresent stimulation field set. At 1278, a response signal is received.The response signal is indicative of effects of the neurostimulationdelivered according to the stimulation program specifying the presentstimulation field set. In various embodiments, the response signal caninclude a user input indicating the patient's perception of the deliveryof the neurostimulation and/or a biomarker signal indicative of effectsof the delivery of the neurostimulation in the patient. In variousembodiments, the received response signal is analyzed for intended andunintended effects of the neurostimulation. Based on the analysis,effects information can be produced to allow for determination ofwhether the present stimulation field set is optimized based on one ormore optimization criteria.

At 1279, the present stimulation field set is reverted to the pre-updatepresent stimulation field set in response to the response signalindicating an unacceptable change to the effects indicated by theresponse signal. The unacceptable change can include a decrease in theintended effect and/or an increase in the unintended effect. After thereverting (i.e., removal of the present stimulation field, the latestfield evaluated), the following may happen: (1) there is a reduction inthe unintended effect, and (2) there is a reduction in the intendedeffect. As such, it is desirable to make a change that accomplishes (1)without (2) occurring.

In one embodiment, in response to the increase in the unintended effect,after the reverting, one or more blocking fields are added. The deliveryof neurostimulation energy to the one or more blocking fields has ablocking effect in preventing the delivery of neurostimulation energyfrom causing an unintended effect or reducing that unintended effect.The blocking effect can be achieved, for example, by allowing for a“blocking pulse” to precede a stimulating pulse, for the purpose ofpreventing the stimulation at a portion of the present stimulation field(the portion responsible for the unintended effect). Thus, a “blockfield” refers to a field to which the blocking pulse is delivered. Thisblocking pulse would necessarily use a blocking field that only blockspart of the present stimulation field because it is not desirable toblock the intended effect. The placement of such a blocking field mayrequire a trial-and-error process, or multiple blocking fields may beset to cover the present stimulation field and one or more blockingfields are then removed by following the subtraction-based programmingmethod as applied to optimizing a blocking field set.

In another embodiment, in response to the increase in the unintendedeffect, after the reverting, the present stimulation field set ismodified for a field shape providing for at least one of use of aninherent blocking effect or use of hyperpolarizing lobes to prevent thedelivery of neurostimulation energy from causing an unintended effect orreducing that unintended effect. The shape of the present stimulationfield set can be changed in some way. For example, the presentstimulation field set can be split into multiple smaller fields beforethe performance of method 1275 continues, or the present stimulationfield can be adapted to block a portion of itself and then theperformance of method 1275 continues with evaluating differentplacements of the blocking portion. Hyperpolarizing lobes refers to thelobes of the activating function. One technique for blocking is toadjust the present stimulation field set such that a portion where theactivating function was depolarizing becomes hyperpolarizing. As anexample, for fibers of passage where the activating function is a seconddifference of the voltage, addition of anodic current in the region tobe blocked can be used to achieve the hyperpolarization. When current isto be conserved, cathodic current can be added to the case electrode, orperhaps to another part of the present stimulation field.

At 1280, steps 1276, 1277, 1278, and 1279 are repeated until the presentstimulation field set is determined to be the optimal stimulation fieldset according to the one or more optimization criteria. In variousembodiments, the optimal stimulation field set is identified from a listof stimulation field sets. The list can rotate through all possiblestimulation fields provided for by the plurality of electrodes. Theinitial stimulation field set can specify many stimulation fields eachdefined by one or more electrodes selected from the plurality ofelectrodes. In one embodiment, performance of method 1275 stops inresponse to identification of any stimulation field set that satisfiesthe one or more optimization criteria (i.e., the list of stimulationfield sets can include multiple optimal stimulation field sets, andidentification of one of them is sufficient). In another embodiment,performance of method 1275 stops in response to all the stimulationfield sets on the list being evaluated (i.e., the list of stimulationfield sets includes one optimal stimulation field set).

FIGS. 13A-E each illustrate an embodiment of a paddle electrode 1382 tobe surgically implanted for delivering neurostimulation, with FIGS.13B-E each illustrating an example of a stimulation field set. FIG. 13Ashows paddle electrode 1382 with an electrode array including 30electrodes (also referred to as contacts) 1306. FIG. 13B shows anexample of a stimulation field set with 15 bipolar stimulation fields1384. The illustrated stimulation field set can be stimulatedsequentially. If the stimulation results in the coverage desired (evenas part of a super set), then a placement of paddle electrode 1382 inthe patient can be considered appropriate, and fine tuning can bepost-operationally performed according to the subtraction-basedprogramming paradigm. FIG. 13C shows another example of a stimulationfield set including 9 tripolar fields 1384, with target poles or anotherarbitrary field assignment used. The stimulation fields can overlap. Thecenter of the array can be preferentially evaluated. FIG. 13D showsanother example of a stimulation field set including 6 bipolar fields1384. FIG. 13E shows another example of a stimulation field setincluding 7 stimulation fields 1384 with different shapes. These shapescan be based on physical electrodes, target poles, and/or other fieldparadigm converted to physical electrodes.

FIGS. 14A-E each illustrate an embodiment of an electrode array atdistal end of a lead 1408 to be percutaneously implanted for deliveringneurostimulation, with FIGS. 14B-E each illustrating an example of astimulation field set. FIG. 14B shows an example of a stimulation fieldset with 6 bipolar stimulation fields 1484 using electrodes 1406 on lead1408. FIG. 14C shows an example of a stimulation field set with 9tripolar stimulation fields 1484 using electrodes 1406 on leads 1408A-B.FIG. 14D shows an example of a stimulation field set with 5 bipolarstimulation fields 1484 using electrodes 1406 on leads 1408A-B. FIG. 14Eshows an example of a stimulation field set with 4 multipolarstimulation fields 1484 using electrodes 1406 on leads 1408A-B.

In various embodiments, the examples of stimulation field sets asillustrated in FIGS. 13 and 14 can be used for optimizing a stimulationfield set according to the subtraction-based programming paradigm. Ifdelivery of the neurostimulation to a stimulation field set results inthe coverage desired (even as part of a super set), then the placementof paddle electrode 1382 or lead 1408 can be considered appropriate forthe patient, and fine tuning can be done later to substantially expeditean implantation process in the operation room. The subtraction-basedprogramming paradigm provides for a method for the post-operational finetuning.

FIG. 15 illustrates an embodiment of a subtraction-based programmingmethod 1585 as an application of methods 1170 and 1275. At 1586,neurostimulation is delivered to many stimulation fields using anelectrode array, with the goal of stimulating target tissue to result inintended effect(s) and the likelihood of stimulating non-target tissueto result in unintended effect(s). At 1587, effects of theneurostimulation is evaluated. If the effects includes the intendedeffect(s) but not unintended effect(s), the performance of method 1585stops at 1589. If the effects includes the intended effect(s) andunintended effect(s), and removal of each stimulation field from themany stimulation fields has been attempted, the performance of method1585 also stops at 1589. If the effects includes the intended effect(s)and unintended effect(s), but removal of one or more stimulation fieldsfrom the many stimulation fields have not been attempted, one or morestimulation fields are removed at 1590. At 1591, whether the intendedeffect(s) are compromised is determined. If the intended effect(s) arenot compromised, the performance of method 1585 processes back to 1587for another iteration. If the intended effect(s) are compromised, theone or more stimulation field removed at 1590 are returned to the set ofstimulation fields prior to the performance of step 1590, and then theperformance of method 1585 processes back to 1587 for another iteration.

In other words, according to method 1585, following stimulation of manystimulation fields, stimulation fields are removed and response to thestimulation is evaluated. The removal of additional stimulation fieldscan stop once any stimulation field to which the stimulation results inunintended effect(s) has been removed, or when removal of allstimulation fields has been attempted (such that no more removal ispossible without compromising the intended effect(s). In variousembodiments, “many” stimulation fields can include at least 2stimulation fields or at least 4 stimulation fields. Stimulation of themany stimulation fields can be delivered sequentially, one field at atime, using an electrode array such as one of those illustrated in FIGS.13 and 14.

FIG. 16 illustrates another embodiment of a subtraction-basedprogramming method 1685 as an application of methods 1170 and 1275. At1686, neurostimulation is delivered to many stimulation fields using anelectrode array, with the goal of stimulating target tissue to result inintended effect(s) and reduce the likelihood of stimulating non-targettissue to result in unintended effect(s). If removal of each stimulationfield from the many stimulation fields has been attempted, theperformance of method 1685 also stops at 1689. If removal of one or morestimulation fields from the many stimulation fields have not beenattempted, one or more stimulation fields are removed at 1690. At 1691,whether the intended effect(s) are compromised is determined. If theintended effect(s) are not compromised, the performance of method 1685processes back to 1688 for another iteration. If the intended effect(s)are compromised, the one or more stimulation field removed at 1690 arereturned to the set of stimulation fields prior to the performance ofstep 1690, and then the performance of method 1685 processes back to1688 for another iteration.

In other words, method 1685 is the same as method 1585 except for thepurpose of maximizing energy efficiency, removal of all the stimulationfields is attempted even after an adequate number of stimulation fieldshas been removed to eliminate the unintended effect(s).

Various methods can be used to determine an order of removal of thestimulation field from the initial stimulation set (including “many”stimulation fields). One example includes using a simplex orsimplex-like search method that is initialized with a polygon thatincludes all the stimulation field of the initial stimulation field set,and iteratively changes the shape of the polygon and reduces the area ofthe polygon. Another example includes initiating multiple simplices withdifferent starting conditions to account for the possibility of multiplelocal minima. Additional examples can include golden-section orFibonacci-based search methods. In various embodiments, non-linearsearch methods with one or more initial conditions can be used. Invarious embodiments, non-linear biologically inspired methods thataccount for multiple optima or regions of interest (ROIs) can be used,such as genetic algorithms, swarm algorithms, etc.

FIG. 17A-F each illustrate an embodiment of part of method 1585 or 1685showing a step in performing the method using paddle electrode 1382including an array of electrodes 1306. FIG. 17A-F also show stimulationfields 1784, a target region 1794 to which the delivery of theneurostimulation results in the intended effect(s), and side-effectregions 1796 to which the delivery of the neurostimulation results inthe unintended effect(s). The optimal stimulation field set shouldinclude one or more stimulation fields that covers target region 1794without covering side-effect regions 1796.

FIG. 17A shows many stimulation fields 1784 cover both target region1784 and side-effect region 1796. For the operational room setting,placement of paddle electrode 1382 is adequate because target region1794 can be stimulated. FIG. 17B shows removal of some of stimulationfields 1784 that results in less coverage of side-effect region 1796,while target region 1784 is still covered. FIG. 17C shows furtherremoval of some of stimulation fields 1784 that results in furtherreduced coverage of side-effect region 1796, while target region 1784 isstill covered. FIG. 17D shows further removal of some of stimulationfields 1784 that results in reduced coverage of target region 1784. FIG.17E shows returning of the removed stimulation fields 1784 to restorethe set of stimulation fields 1784 of FIG. 17C, thereby restoringcoverage of target region 1784. FIG. 17F shows removal of additionalstimulation fields 1784 that eliminates coverage of side-effect region1796, while target region 1784 is still covered. Thus, the stimulationfield set is optimized because it covers target region 1794 withoutcovering side-effect regions 1796, as illustrated in FIG. 17F.

FIG. 18A-E each illustrate an embodiment of part of method 1585 or 1685showing a step in performing the method using paddle electrode 1382including an array of electrodes 1306. FIG. 18A-E also show stimulationfields 1784, target regions 1894, and side-effect regions 1896. FIG.18A-E show an example where target and side-effect regions arejuxtaposed, and addition of “blocking” (in addition to or in place ofremoving) is used to reduce the unintended effect(s). Thus, FIG. 18A-Efurther show blocking fields 1898 to which the delivery of theneurostimulation has a blocking effect in preventing the delivery of theneurostimulation from causing unintended effect(s). In some embodiments,blocking fields 1898 are smaller than stimulation fields 1784 to providefor higher resolution blocking.

FIG. 18A shows many stimulation fields 1784 cover both target region1884 and side-effect region 1896. For the operational room setting,placement of paddle electrode 1382 is adequate because target region1794 can be stimulated. FIG. 18B shows removal of some of stimulationfields 1784 that results in nearly no coverage of side-effect region1796, while target region 1784 is not adequately covered. FIG. 18C showsrestoration of a stimulation fields 1784 that results in increasedcoverage of side-effect region 17%, while target region 1784 isadequately covered. FIG. 18D shows addition of blocking fields 1898 toblock the unintended effect(s) resulting from the stimulation fieldadded as shown in FIG. 18C. The blocking effect can be achieved, forexample, using pre-pulses or conditioning pulses. Examples of blockingare discussed in U.S. Pat. Nos. 7,742,810; 8,311,644; 8,788,059; and9,375,575, all of which are assigned to Boston ScientificNeuromodulation Corporation and incorporated herein by reference intheir entireties. FIG. 18E shows a solution to the unintended effect(s)being an alternative to that illustrated in FIG. 18D. Stimulation fields1784 are modified in a manner that results in blocking or notstimulating being inherent in the field shape or the use ofhyperpolarizing lobes.

In various embodiments, the system for performing the subtraction-basedprogramming method, such as a neurostimulation system in which system960 or 1060 is implemented, may be required to change stimulation fields(including removing stimulation fields) within a short period of time.In one embodiment, it is desirable to rotate through all of thestimulation fields within 25 ms (40 Hz). For example, 50 stimulationfields running at 40 Hz each results in an aggregate frequency of 2,000Hz (i.e., the period of time T=500 μs). Therefore, charge of stimulationfields must be injected and properly recovered within 500 μs, assumingall the stimulation fields use the same pulse duration (PD, includingcharge injection and recovery phases). However, it is not required thatall the stimulation fields use the same PD. If different PDs are used,the sum of PD1 through PD50 should be less than or equal to 25 ms,assuming that all the stimulation fields run at the same frequency.However, the stimulation fields can run at different frequencies andeven irregular patterns, and additional flexibility can be built intothe system. In another embodiment, it is desirable to rotate through allof the stimulation fields within 50 ms (20 Hz). For example, 50stimulation fields running at 20 Hz each result in an aggregatefrequency of 1,000 Hz (i.e., the period of time T=1,000 μs). Therefore,charge of stimulation fields must be injected and properly recoveredwithin 1,000 μs, assuming all the stimulation fields use the same PD.However, it is not required that all the stimulation fields use the samePD. If different PDs are used, the sum of PD1 through PD50 should beless than or equal to 50 ms, assuming that all the stimulation fieldsrun at the same frequency. However, the stimulation fields can run atdifferent frequencies and even irregular patterns, and additionalflexibility can be built into the system.

In one embodiment, multiple stimulation fields that are an adequatedistance apart from each other (such that interaction is sufficientlysmall) can be run at the same instant to preserve bandwidth. Examples ofadequate distances apart can reasonably include 8 mm or more, 10 mm ormore, or 12 mm or more.

FIG. 19 illustrates an embodiment of tools for editing a stimulationfield set using a GUI, such as user interface 310 or 810. In oneembodiment, the table of illustrated tools and optionally theirdescriptions can be displayed for the user on the GUI when needed. Invarious embodiments, the GUI can support manual removal, for example,with an eraser tool. The tools can enable manual removal of one or morestimulation fields in a predetermined or random sequence, with supportto quickly undo and skip removal of a stimulation field that has beendetermined to be important to provide for the intended effect(s). In oneembodiment, the GUI can automatically undo and skip removal of astimulation field when such a need is determined.

In various embodiments, the subtraction-based programming paradigm caninclude automated or semi-automated processes (e.g., an automated orsemi-automated binary search or another optimization routine fordetermining an order of removal of stimulation field(s). One embodimentcan include use of heuristic search rules. Genetic or other algorithmsthat support multiple non-contiguous foci can also be found desirableand used.

It is to be understood that the above detailed description is intendedto be illustrative, and not restrictive. Other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. The scope of the invention should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed is:
 1. A method for delivering neurostimulation totissue of a patient using a stimulation device coupled to a plurality ofelectrodes and controlling the delivery of the neurostimulation by auser, the method comprising: delivering the neurostimulation accordingto a stimulation program specifying a present stimulation field setincluding one or more stimulation fields each defined by a set of activeelectrodes selected from the plurality of electrodes; setting thepresent stimulation field set to an initial stimulation field setspecifying a plurality of stimulation fields and allowing for thedelivery of the neurostimulation to produce an intended effect in thepatient; and identifying an optimal stimulation field set that satisfiesone or more optimization criteria by removing one or more stimulationfields from the initial stimulation field set, the optimal stimulationfield set including one or more stimulation fields based on a subset ofthe plurality of stimulation fields of the initial stimulation fieldset.
 2. The method of claim 1, wherein the one or more stimulationfields are each further defined by a distribution of energy of theneurostimulation over the active electrodes.
 3. The method of claim 1,wherein identifying the optimal stimulation field set comprises:removing at least one stimulation field from the present stimulationfield set to update the present stimulation field set; causing thestimulation device to deliver the neurostimulation according to thestimulation program specifying the present stimulation field set;receiving a response signal indicative of effects of theneurostimulation delivered according to the stimulation programspecifying the present stimulation field set; reverting the presentstimulation field set to the pre-update present stimulation field set inresponse to the response signal indicating an unacceptable change to theeffects indicated by the response signal; and repeating the removing,causing, receiving, and reverting until the present stimulation fieldset is determined to be the optimal stimulation field set according tothe one or more optimization criteria.
 4. The method of claim 3, whereinreceiving the response signal comprises receiving a user inputindicating the patient's perception of the delivery of theneurostimulation.
 5. The method of claim 3, wherein reverting thepresent stimulation field set to the pre-update present stimulationfield set in response to the response signal indicating the unacceptablechange to the effects indicated by the response signal comprisesreverting the present stimulation field set to the pre-update presentstimulation field set in response to the response signal indicating atleast one of a decrease in the intended effect or an increase in anunintended effect.
 6. The method of claim 5, further comprising, afterthe reverting in response to the response signal indicating the increasein the unintended effect, adding to the present stimulation field setone or more blocking fields to which the delivery of theneurostimulation has a blocking effect in preventing the delivery of theneurostimulation from causing the unintended effect or reducing theunintended effect.
 7. The method of claim 5, further comprising, afterthe reverting in response to the response signal indicating the increasein the unintended effect, modifying a shape of the present stimulationfield set to prevent the delivery of the neurostimulation from causingthe unintended effect or reduce the unintended effect.
 8. The method ofclaim 3, further comprising analyzing the received response signal toproduce effects information allowing for determination of whether thepresent stimulation field set is the optimal stimulation field set basedon the one or more optimization criteria.
 9. The method of claim 8,wherein the effects information indicates the unacceptable change to theeffects of the neurostimulation delivered according to the stimulationprogram specifying the present stimulation field set.
 10. The method ofclaim 9, further comprising declaring the present stimulation field setto be the optimal stimulation field set in response to the effectsinformation indicating that the intended effect is maintained withoutcausing an unintended effect.
 11. The method of claim 10, furthercomprising declaring the present stimulation field set to be the optimalstimulation field set in response to the effects information indicatingthat the intended effect is maintained with energy of the deliveredneurostimulation being minimized.
 12. The method of claim 9, furthercomprising declaring the present stimulation field set to be the optimalstimulation field set in response to the effects information indicatingthat the intended effect is maintained while one or more unintendedeffects are minimized.
 13. The method of claim 8, wherein identifyingthe optimal stimulation field set comprises identifying the optimalstimulation field set identified from a list of test stimulation fieldsets, and the repeating comprises repeating the removing, causing,receiving, and reverting until each test stimulation field set on thelist is set to the present stimulation field set to result in theeffects information allowing for the optimal stimulation field set toidentified from the list for best satisfying the one or moreoptimization criteria.
 14. A system for delivering neurostimulation totissue of a patient using a stimulation device coupled to a plurality ofelectrodes and controlling the delivery of the neurostimulation by auser, the system comprising: a programming control circuit configured toprogram the stimulation device for delivering the neurostimulationaccording to a stimulation program specifying a present stimulationfield set including one or more stimulation fields each defined by a setof active electrodes selected from the plurality of electrodes; and astimulation control circuit configured to determine the stimulationprogram, the stimulation control circuit including field programmingcircuitry configured to: set the present stimulation field set to aninitial stimulation field set specifying a plurality of stimulationfields and allowing for the delivery of the neurostimulation to producean intended effect in the patient; and identify an optimal stimulationfield set that satisfies one or more optimization criteria by removingone or more stimulation fields from the initial stimulation field set,the optimal stimulation field set including one or more stimulationfields based on a subset of the plurality of stimulation fields of theinitial stimulation field set.
 15. The system of claim 14, wherein thefield programming circuitry configured to identify an optimalstimulation field set by: removing at least one stimulation field fromthe present stimulation field set to update the present stimulationfield set; causing the stimulation device to deliver theneurostimulation according to the stimulation program specifying thepresent stimulation field set; receiving a response signal indicative ofeffects of the neurostimulation delivered according to the stimulationprogram specifying the present stimulation field set; reverting thepresent stimulation field set to the pre-update present stimulationfield set in response to the response signal indicating an unacceptablechange to the effects indicated by the response signal; and repeatingthe removing, causing, receiving, and reverting until the presentstimulation field set is determined to be the optimal stimulation fieldset according to the one or more optimization criteria.
 16. The systemof claim 15, further including a user input device configured to receivea user input indicative of the patient's perception of the delivery ofthe neurostimulation, and wherein the stimulation control circuitfurther comprises: a response input configured to receive a responsesignal indicative of effects of the neurostimulation, the responsesignal including the received user input; and response analysiscircuitry configured to analyze the received response signal and produceeffects information allowing for the determination of whether thepresent stimulation field is the optimal stimulation field set accordingto the one or more optimization criteria.
 17. The system of claim 16,wherein the field programming circuitry is configured to declare thepresent stimulation field set to be the optimal stimulation field set inresponse to the effects information indicating that the intended effectis maintained without causing an unintended effect.
 18. The system ofclaim 16, wherein the field programming circuitry is configured toidentify the optimal stimulation field set from a list of teststimulation field sets, and the repeating comprises repeating theremoving, causing, receiving, and reverting until each test stimulationfield set on the list is set to the present stimulation field set toresult in the effects information allowing for the optimal stimulationfield set to identified from the list for best satisfying the one ormore optimization criteria.
 19. A non-transitory computer-readablestorage medium including instructions, which when executed by a machine,cause the machine to perform a method for delivering neurostimulation totissue of a patient using a stimulation device coupled to a plurality ofelectrodes and controlling the delivery of the neurostimulation by auser, the method comprising: delivering the neurostimulation accordingto a stimulation program specifying a present stimulation field setincluding one or more stimulation fields each defined by a set of activeelectrodes selected from the plurality of electrodes; setting thepresent stimulation field set to an initial stimulation field setspecifying a plurality of stimulation fields and allowing for thedelivery of the neurostimulation to produce an intended effect in thepatient; and identifying an optimal stimulation field set that satisfiesone or more optimization criteria by removing one or more stimulationfields from the initial stimulation field set, the optimal stimulationfield set including one or more stimulation fields based on a subset ofthe plurality of stimulation fields of the initial stimulation fieldset.
 20. The non-transitory computer-readable storage medium of claim19, wherein identifying the optimal stimulation field set comprises:removing at least one stimulation field from the present stimulationfield set to update the present stimulation field set; causing thestimulation device to deliver the neurostimulation according to thestimulation program specifying the present stimulation field set;receiving a response signal indicative of effects of theneurostimulation delivered according to the stimulation programspecifying the present stimulation field set; reverting the presentstimulation field set to the pre-update present stimulation field set inresponse to the response signal indicating an unacceptable change to theeffects indicated by the response signal; and repeating the removing,causing, receiving, and reverting until the present stimulation fieldset is determined to be the optimal stimulation field set according tothe one or more optimization criteria.